Hermetically sealed switch



Aug- 1957- J. F. EDWARDS, JR.. :rm. 2,302,912

HERIETICALLY sumo svmca Filed Jan. 11, 1956 INVENTORS Johrc R Edwards,Jr.

Lirzdsaq C.Frierzd. BY Kelmebh D. Shaub.

ATTORNEY 2,802,912 HERMETICALLY SEALED swrrcn John F. Edwards, Jr., andLindsay C. Friend, Baltimore, and Kenneth D. Shaub, 'Iimonium, Md.,assigno'rs to Bendix Aviation Corporation, Baltimore, Md., a corporationof Delaware Application January 11, 1956, Serial No. 558,554 6 claims.(Cl; 200- 14 This invention relates to switches of that type havingelectrical contacts located in a sealed enclosure. Such switches areused extensively in areas where explosive gases are or may be present,where it is desired to provide high resistance to arcing by evacuationof the switch chamber or by loading the latter with an inert gas, and innumerous other installations. Prior known switches of this general typeare either more or less complicated and hence relatively expensive tomanufacture, require a relatively high actuating force, or are sensitiveto vibration and mechanical shock; and the primary object of the presentinvention is to provide a switch which will avoid these objectionablefeatures.

Another object is to provide a switch of the hermetically sealed typewhich will accommodate practically any desired number of contacts andwhich at the same time may be set with remarkable ease and reliability.

The foregoing and other objects and advantages will become apparent inview of the following description taken in conjunction with the drawing,wherein:

Fig. 1 is a view in transverse vertical section of a switch inaccordance with the invention;

Fig. illustrates the switch of Fig. 1 incorporated in a so-calledwafer-type switch assembly; and

Fig. 3 is a plan view of the inner or contact side of the wobble endplate of the switch, illustrating a variation in the contact arrangementwith respect to that shown in Figs. 1 and 2.

Referring to Fig. 1 of the drawing, a capsule is generally indicated atit is made up of a base or end plate 11, which may be made ofsubstantially rigid material such as non-corrosive metal, insulation orthe like, and has fixed therein a plurality of upstanding contacts 12,13, etc., which are imbedded in suitable insulating material 14 andprovided with leads as indicated at 15. The opposite end plate,indicated at 16, functions as a wobble switch c-ontactor; in the exampleillustrated in Figs. 1 and 2, it is made of conducting material such ascopper and has substantially centrally thereof a cam depression 17, thesaid plate 16 being connected to the base plate 11 by a bellows portion18, made of spring material embodying sufiicient spring force to drawthe plates 11 and 16toward one another to a position where the lowermostportion of the cam depression 17 bottoms on the plate 11. The springstrength of the bellows portion 18 may vary, depending upon theinstallation to which the switch is adapted. For example, if the switchis used for high altitude service, the spring force of the bellows 18should be sufiicien-t to maintain the base in contact with the inner endof the cam portion 17 at the lowest external pressure to which theswitch may be subjected. Obviously, the biasing effect of the springforce is substantially uniform on all sides of the bellows.

An actuator or set-ting cam is indicated at 19; it has an eccentriccontour and is provided with .a control shaft 20. When this cam isinserted in the cam depression 17 and rotated, the wobble plate 16 maybe selectively rocked 2 into contact with any one or more of thecontacts 12 and 13.

In the wafer switch assembly of Fig. 2, parts which correspond to thoseof Fig. l are given like reference numerals. In this instance the baseis indicated at 11; it is slightly modified in that it is extended atdiametrically opposite points and connected by insulated posts 21 to anindex plate 22. Obviously, if the outer anchor portion ofthe base 11' ismade of insulation material,

the posts need not be insulated. The cam 19 and shaft 20 in thisinstance are conductors, the shaft being extended upwardly and connectedthrough a key section 23 to a coupling member 24, which in turn projectsthrough a bushing 24 and has fixed to the end thereof an adjusting knob25. The section 23 is keyed to a rotatable switch plate 26, carryingwiper blades 27, adapted to wipe a series of spring contacts '28,secured to an intermediate plate 29. The index plate 22 is provided witha series of detent depressions 30 on its under surface, which areadapted to be engaged by one or more detent members 31, mounted onspring strips or arms 32, which are fixed to the coupling member 24 andhence rotate with the latter.

The construction and operation of wafer switches are well known, thenovel feature of the assembly shown in Figure 2 being the switch ofFig. 1. To set the switch, the selector knob 25 is rotated to index anyone or more of the circuits (not shown) which may be interconnectedthrough the said switch. As the knob is rotated, it also impartsrotation to the cam 19, which rocks the wobble plate or cap 16 intoengagement with certain of the contacts 12, 13, etc.

In cases where the switch is to be mounted in an area of explosivegases, the capsule or switch proper of Fig. 1 may be located directly insuch area and the actuating cam rendered accessible for remote control,or as in the installation of Fig. 2, the high voltage circuit may beinterconnected through the switch proper and the low voltage or relaycircuitry by way of the contacts 27 and 28. The switch capsule may bereadily evacuated or loaded with an inert gas; it can easily be designedto resist vibration, acceleration and gravity forces, and its verysimplicity is one of its most important advantages.

In Fig. 3 the wobble plate or cap, here indicated at 16, is made ofinsulated material and is provided with a series of contact strips 33,adapted to engage any selected number of the contacts 12, 13, etc. ofthe plate 11 of Fig. 1, which in this instance would be arranged inarcuate groups. This serves to illustrate how the switch of Fig. 1 maybe conveniently adapted to different switch circuitry.

In other installations, the wobble cap could be provided with circuitconnections direct to selected groups of contacts. These and otheradaptations will be obvious to those working in the electrical arts oncethe basic concept of the invention becomes known.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a switch of the type specified, a capsule made up of opposite endplates connected by a bellows portion comprised of spring materialtending to urge the said plates toward one another, one of said endplates serving as a movable contact plate and carrying a member whichprojects through the chamber defined by the capsule and engages theopposite end plate to provide a fulcrum or pivot point about which saidmovable contact plate is rockable, the other of said end plates having aplurality of contacts projecting therefrom into said chamber, and meansfor actuating said movable contact plate about its fulcrum or pivotpoint to make and break one or more electrical circuits which may beinterconnected by way of said contact plate and contacts.

2. In a switch of the type specified, a capsule made up of opposite endplates joined by a bellows portion of spring material tending to movesaid plates toward one another, one of said plates being provided with aplurality of contacts projecting therefrom into the chamber defined bythe capsule and the opposite end plate serving as a movable contactmember, said movable end plate being provided with a projection whichextends through the chamber and engages the opposite end plate toprovide a rocking or fulcrum point, and cam means rotatable to rock saidconductive end plate about its fulcrum or pivot to make and break one ormore electrical circuits which may be interconnected by way of saidcontact plate and contacts.

3. An hermetically sealed switch comprising a capsule made up ofopposite end plates joined by a bellows portion Ofspring materialtending to move said plates toward one another, one of said plates beingfixed in a definite switch position and provided with a plurality ofcontacts projecting therefrom into the chamber defined by the capsuleand the opposite end plate serving as a movable contact member, saidmovable end plate being formed with a substantially central depressionthe innermost point of which engages the relatively fixed end plate toprovide a pivot point, and rotatable cam means adapted to rock themovable plate about its pivot to make and break one or more electricalcircuits which may be interconnected by way of said contact plate andcontacts, said bellows portion having sufficient spring force tomaintain contact between the relatively-fixed end plate and theinnermost point of said cam depression. 4. An hermetically sealed switchcomprising a capsule made up of opposite .end plates joined by a bellowspor: tion of spring material tending to move said plates toward oneanother, one of said end plates being substantially rigid and fixed in adefinite switch position and having a plurality of contacts projectingtherefrom into the chamber defined by the capsule and the opposite endplate being movable and carrying conductive material for engagement withsaid contacts, said movable end plate being formed with a substantiallycentral depression which extends through the chamber and has itsinnermost point engaging the rigid end plate to provide a rocking orfulcrum point, and a rotatable eccentric cam adapted to engage in saiddepression.

' 5. An hermetically sealed switch comprising a capsule made up ofopposite end plates connected by a bellows portion of spring materialtending to move said plates toward one another, means supporting one ofsaid end plates in a definite fixed switch position, a plurality ofcontacts projecting upwardly from the fixed end plate into the chamberdefined by the capsule, the end plate opposite said fixed plate beingfree to wobble and carrying conductive material for engagement with saidcon-v tacts, said wobble end plate being provided with a substantiallycentral pivot member which extends through the chamber and has itsinnermost point engaging the rigid end plate, a rotatable eccentric camengaging'in said depression, a-shaft projecting from said cam,-andswitch-indexing means associated with said shaft for rotating thelatter.

6. An hermetically sealed switch comprising a capsule made up ofopposite end plates, side walls connecting said plates and formed-atleast in part of collapsible material, one of said plates being fixed ina definite switch position and the other of said plates serving as amovable wobble plate, contacts projecting from one of said plates andadapted to coact with contact elements carried by the other of saidplates, means resiliently biasing the said plates towards one another,said biasing means exerting a substantially uniform biasing force on allsides of the capsule, a member projecting from the movable contact plateaxially through the chamber defined by the capsule and engaging theopposite end plate to provide a fulcrum or pivot point about which saidmovable contact plate has universal wobble movement, and means for.actuating said movable contact plate about the fulcrum or pivot pointprovided by said member to make and break one or more electricalcircuits which may be interconnectedby said contacts.

References Cited in the file of this patent I UNITED STATES PATENTS

